Can we just create the family without reference plane ?

[Anonymous]

  Why we just create the label dimension directly to the face/plane of the geometry ?

  Why do we have to use the reference plane?

  What is the pros and cons between use and not use the reference plane in creating the family ?

[ToanDN]

You don't want to do that.  Reference planes in Revit is like UCS in AutoCAD, virtually every element built in Revit need to based on reference planes.  You can ignore the them when you build your families but will will have paramount hardships come to parametric constraining, especially for hosted families.

To put it another way, it's like driving your car without a steering wheel.  You can still do it by keep hitting the curbs to alter the direction of the car.  But it is not much fun. 

[Anonymous]

   Can you give me some example of bad thing when Creating family and ignore the reference plane?

[Alfredo_Medina]

It's not clear what the purpose of the question is. Building a family without reference plane is actually difficult because all the templates need to have at least 2 reference planes, which cannot be deleted. Those two reference planes mark the origin point of the family. 

[Kimtaurus]

The reference plane defines the origin or insertion point of that family.

Let's say you have a table placed in a room and you want to swap it with a different family. Revit looks at the ref planes to place the new element.

If the family is modelled in a different way then the previous one, the talbe will be placed in another location (if that makes any sense).

So it's not inly important to use them, you also have to be consistent when modelling families.

[chrisplyler · Accepted solution]

If you're just making something very simple - like, let's say a cube - and you don't need different types for different sizes, then sure adding reference planes (and/or reference lines) isn't really necessary and doesn't really do anything to help you.

But for anything more complex than that, you WANT to use them. This is because, whether it's logical or not, Revit makes use of them to be driven by things (parameters), to drive things (geometry/relationships), to provide control grips, and to allow snapping/aligning/dimensioning to other elements in a project.

Want to build a counter top that snaps it's backsplash up against a wall? Reference plane. Want that cabinet to have control grips on the sides so you can stretch it out to side walls or over cabinetry? Reference planes. Want a hole cut out in the counter top for a sink? Reference planes. Want that sink hole to allow positioning and sizing for various sink models and locations? REFERENCE PLANES!!!

[Sahay_R]

Reference planes are the skeleton of the family. You create the skeleton first, apply dimensional constraints and families, and flex it to see if it works.

It is particularly beneficial if you are creating a family with types - for instance, casework base cabinets that have multiple heights and sizes. With casework, for instance, every time you need to create a new type all you have to do is change the dimensions which will then control the geometry to modify the family. If you want to control the dimensions of the family, you will use reference planes. This is done with less effort - you only need to constrain the reference planes, not constrain every piece of geometry.

There are cases where you don't need reference planes - for instance, if you are bringing in geometry from some other program. This will most probably come in a 'dumb' geometry and you will not be able to exert any dimensional control over it. 

[tosapol_engr]

Can't agree more .. 🙂

[jschulien]

I actually agree with this way of thinking.  It would be nice to build a family or component free of referencing planes until after the family is done.  the way the system is set up now it stifles imagination and creativity.  Revit seems to only be able to build something if the user knows what it is they are building where it exists and how they want it to move.  sometimes you just want to build and see where it goes.  you should be able to place it in a building and figure out what you want it to do later.

[constantin.stroescu]

as a matter of fact ,on the market , there are a lot of families that do not use Reference Planes. These are "frozen" families that allows only fixed dimensions.  If a manufacturer fabricates only one type of object with predefined dimensions , he  will not make a parametric family ,then  he does  not need Reference Planes except those which define the center.

I hate these families because you are not able to add new dimensions . As an example a piece of furniture will have a single choice for Length,Depth and Height...

But if you want a Generic Family that contains more dimensional types - geometric parameters, then you will certainly need Reference Planes.

[Anonymous]

So I'm printing a set of drawings....there is just a thing in a room...architect asks what it is... It's something, I don't know what it is yet, just there until I figure out what it is.

Um.  Okay.  Might be wise to stick to paper sketches until you know what something is going to be.

[Sahay_R]

Revit's major strength is the ability to control geometry by parameters. Reference planes allow you to precisely control the dimensions of the geometry and make it 'flex'. One set of geometry can be made to have multiple size types. 

In-place modeling would be the route to take if you want to see where the geometry goes in the context of the building. Once you are sure of the geometry, the in place model can be converted into a regular family 

[whp.m.owens]

My two cents; comments which may already have been addressed in previous posts...

From my point of view, I would also "love" to get rid of reference planes, because you essentially have to draw each piece of geometry twice, and it does require a shift in how content is created. (You could also just create the geometry first, and parameterize later.

Parameterization is one thing. Here reference planes are critical and I don't think I'll waste too much space making arguments for them. In short, reference planes are a skeleton you can build relationships on and host geometry to. This carries over into the project environment as well when you start assigning dimension references to objects.

That is the crux of the argument for reference planes; the method which Revit uses to maintain relationships and it is done with reference planes. You could host without reference planes, but then you start building relationships to elements which change in a way that breaks relationships. (Deleting a line in a profile sketch, or using visibility parameters for static families.) Revit has no way to maintain the IDs of these individual elements.

Example: You build a family with two pieces of geometry. Type A and Type B. You control the family type with a yes/no visibility parameter. You place Type A, dimension it, and go home. Tomorrow morning, it needs to be changed to Type B. You change it, but all dimensions are lost. These are two geometries which have no shared relationship.

I would also recommend assigning the type to reference planes. Generally I always assign the "top, bottom, left, right, back, front" and "center" references. Otherwise, everything else is "not a reference." For more complex families, these can come into play, but then nested families come into play greatly simplifying the family editing.

[charles.roucher]

Short answer: no. Even in families you need to set a reference plan. Are reference plans useful? Yes... and no. While they allow some very basic geometrical accuracy for modelling, when it comes to construction, it is your Levels and Gridlines that will be used as reference, therefore no one will see the reference plans you have created. So presumably reference plans are designed to assist and fair enough there are instances where it is handy especially in large scale projects. The problem is Revit offers NO MODELLING ALTERNATIVE, so when your modelling gets a little bit more complex than drawing straight lines, that's where other modelers bit the crap out of Revit. Let's face it Revit SNAPPING is downright atrocious but even if it was as good as AutoCAD or even better in 3D Archicad you would still not be able to do this for instance a bi-directional curve:

With a modeler that offers an accurate point to point snap, I should even be able to snap at midpoint of a model element's edge, and if the modeler is really performant the resulting curve should lock itself where the route is optimal, and this for every point to point section I want to create. Revit does not offer this because Revit was not build for anything outside reference planes. To me, reference planes is a lure. Who uses reference planes for everyone of your model elements? I only use them to cut things and even that has its limitations because if you want to use several reference planes each at different levels to say... cutting a single wall, you can't. Revit cannot do it. For that you will have to truncate your single wall in as many little walls as you have reference planes, and if you add some degree of difficulty to this scenario by making the wall curved... Revit will go AWOL. Revit is a descent program but in the aspect of modeling anyone who has used Archicad, Rhino, SketchUp will be left frustrated by its inability to snap "hand free" and people who use AutoCAD also find Revit does not deliver the goods at Documentation level. This is why Autodesk clients are so frustrated, they don't want small upgrade implementations to their Revit software, they want proper 3D/2D capability out of the box that does not require a gazillion of procedures, add-ins or Dynamo scripts to achieve a simple point to point snapping. End users want that too.  

[tnievesP53K8]

The problem with that is Revit is designed to build things in a way that is smart and easy to reuse and not create a ton of families that are slightly different. Constraints help with this significantly. Would it be nice if Revit would allow it's origins to be a bit more flexible? Sure. That definitely applies to models where almost every one I've seen seems to ignore the internal origin. However I have also used other 3D software such as blender, Unreal, Rhino and SketchUp that don't have reference planes and I honestly wish they did. It makes it easier to understand an objects center, it's constraints, and how it might function. or stretch. They could use a good amount of polish to make them less confusing (sometimes it's hard to clearly understand how they work constraint wise because you can't always set anchors) but in general they make modeling easier. If your family doesn't need to stretchy then you may only need to deal with the two origin reference planes which you CAN unpin and move technically (though I'm not sure if they also have an invisible origin like models or if the origin truly is defined by these reference planes)

Also, another thing to note about reference planes, is besides them helping with parametric design, they also can make a huge difference when hosting. Using the Left, Right, Center, Bottom, Top reference planes help define when an element should be considered constrained. For example. if you create a door with a sidelite that can be toggled on to the left or right of the door, having the reference planes indicate left, right, and middle help keep the door in the same location, even if the family grows in width when turning on the sidelite. It's also great for things like panels where a pattern might overlap. Since families are primarily for creating objects used in buildings and construction, there shouldn't be the same level of creativity needed for them unless you are creating some very custom object. (which happens but not as much as creating already existing objects).

Hopefully this helps explain their importance. If you really want to create some crazy shapes that don't have any dimensional constraints you could always import a blender object into Revit I believe. You won't be able to make it parametric later, but I imagine if reference planes are that prohibiting to it's design, it probably can't be parametric anyway.